The purpose of the Contract is to conduct toxicity studies of up to six months duration in rodents. These studies shall be conducted according to the procedures and requirements of the General Statement of Work for the Systems Toxicity Branch and study protocols developed for specific therapeutics. Such studies shall 1) provide a screen for AIDS therapeutics, administered alone or in combination to rats and/or mice, for general, reproductive/developmental, and other systems-specific toxicities, and 2) provide a mechanism to study the development of general toxicities in rats and mice administered AIDS therapeutics, alone or in combination, over an extended period of time. The following tasks shall be performed: TASK Ia: REPRODUCTIVE/DEVELOPMENTAL GENERAL TOXICITY STUDIES ON RODENTS EXPOSED TO A SINGLE THERAPEUTIC AGENT OR A COMBINATION OF THERAPEUTICS. TASK Ib: 28-DAY TOXICITY STUDIES ON RODENTS EXPOSED TO A SINGLE THERAPEUTIC OR A COMBINATION OF THERAPEUTICS. TASK II: 13-WEEK (90-DAY) TOXICITY STUDIES ON RODENTS EXPOSED TO A SINGLE THERAPEUTIC OR A COMBINATION OF THERAPEUTICS. TASK III: 6-MONTH TOXICITY STUDIES ON RODENTS EXPOSED TO A SINGLE AGENT OR A COMBINATION OF AGENTS.